One of the most important effects following a nuclear detonation event is a strong pulse of electromagnetic energy released in very broad frequency bandwidth. This electromagnetic energy is primarily distributed as gamma-ray and X-ray radiation; “thermal flash” that includes: ultraviolet (UV), visible, and infrared (IR) light; radio-frequency (RF) waves; and electromagnetic pulse (EMP).
Many systems rely on information displays, such as, for example, an active matrix liquid crystal display (AMLCD). Conventional information displays, however, are susceptible to damage by electromagnetic energy. FIG. 1 depicts a conventional active matrix liquid crystal display module 1. Active matrix liquid crystal display module 1 is positioned in front of a backlight (not shown) and modulates light from the backlight to provide a graphical image to a viewer. Active matrix liquid crystal display module 1 includes a glass laminate stack 11, which contains an electrically active matrix of pixel elements that are driven by row driver circuits 12 and column driver circuits 13 to produce the light modulation.
FIG. 2 shows a glass laminate stack 11 of a conventional active matrix liquid crystal display. Glass laminate stack 11 consists of a front transparent substrate (also called a front passive plate) 2 facing the viewer and a back substrate (also called a rear active plate) 3 positioned in front of a backlight assembly sandwiching a thin layer of liquid crystal material 15.
FIGS. 3 and 4 show further details of a front transparent substrate 2 of a conventional active matrix liquid crystal display. A front polarizer film 21 (also referred to as an analyzer) covers the viewer-facing side of the front transparent substrate 2. The opposing side of the front transparent substrate 2 is covered in layered sequence from the glass substrate by color filters 22 and transparent row electrodes 23.
FIGS. 5 and 6 show further details of a back substrate 3 of a conventional active matrix liquid crystal display. A rear polarizer film 31, polarizing light in a sense that is opposite of the front polarizer film 21, in the case of normally white conventional active matrix liquid crystal display, covers the backlight-facing side of back substrate 3. The opposing side of back substrate 3 is covered with active circuitry 30 including column electrodes 33 and pixel transistors 34. The active circuitry 30 is fabricated from silicon structures, such as, amorphous silicon, polysilicon, and single crystal silicon.
Because AMLCDs absorb a percentage (currently >90%) of light energy, thermal flash radiation from a nuclear detonation can damage information displays by overheating absorbing materials within the information displays, such as, for example, polarizers and color filters. Thermal radiation can also cause liquid crystals to outgas or boil, resulting in void formation and cell-gap non-uniformity. Gamma radiation and X-rays knock electrons free from atomic nuclei that are struck. In order to protect an electronic device, electrons that are knocked loose in a shielding layer should be conducted immediately to ground. Electromagnetic pulse (EMP) and electromagnetic interference (EMI) affect information displays through three mechanisms, electric field (E-field), magnetic field (h-field), and radio frequency (RF) coupling.
Challenges hardening AMLCDs arise because conventional methods of hardening that maximize the absorption of damaging radiation also significantly reduce the display luminance reaching the viewer. Problems also arise because conventional shielding mechanisms, such as mesh windows, induce undesirable moiré effects.
Thus, there is a need to overcome these and other problems with the prior art and to provide nuclear hardening methods and apparatus that maximize luminance of the display while selectively absorbing damaging radiation.